Over 4,000 chemicals are found in tobacco smoke. [7] 38 of the chemicals found in cigarette smoke are listed as carcinogenic in the U.S. Surgeon General's report in 1989. [4]
Three thousand-five hundred of the chemicals in the smoke make up only 5% of the weight of the cigarette smoke. This is a stream of minute particles, known as the particulate phase and visible as "smoke."[3] The major chemical in the particulate phase is nicotine. Aside from the nicotine and water, the rest of the chemicals in the particulate phase are called "tar". Many carcinogens [cancer-causing chemicals] have been identified in cigarette tar, including benzene and benzo(a)pyrene. [7]
The rest of the cigarette's output is invisible, coming out as chemicals that are vapors or gases. There are about 500 different gaseous chemicals,[7] including some common gases such as nitrogen, ammonia, and carbon dioxide, as well as some more dangerous gases, such as carbon monoxide, formaldehyde, acrolein, hydrogen cyanide, acetaldehyde, and nitrogen oxides. [3]
The smoke inhaled by the smoker, and subsequently exhaled into the room, is called "mainstream" smoke. Sidestream smoke emerges from the burning tip of the cigarette between puffs. Because the cigarette tip burns hotter while the smoker inhales, a slightly different mix of chemicals is created for the smoker to inhale than while the cigarette burns between puffs. Once inhaled, the smoker's body effectively keeps substantial parts of the smoke, such as nicotine, tar, and some of the gases.[3] Exhaled mainstream smoke has different proportions of chemicals than "sidestream" smoke.
From the bystander's perspective, the sidestream smoke causes more concern. "Many toxins are present in higher concentrations in sidestream smoke than in mainstream smoke and, typically, nearly 85% of the smoke in a room results from sidestream smoke."[5]
A list of things found in cigarette smoke, from the EPA's report on Environmental Tobacco Smoke, or ETS: http://www.gasp.org/chemicals.html or in the report itself (see tables 3.1 and 3.2): http://www.epa.gov/ncea/ets/etsindex.htm
More information on some of the ingredients: http://www.ash.org.uk/html/factsheets/html/fact12.html
Additional information on specific groups of chemicals in cigarette smoke: http://www.smoke-free.ca/factsheets/Chemicals.htm
For a listing of how the contents of sidestream smoke contribute to air pollution: http://www.smoke-free.ca/factsheets/pdf/1996TotalChem.PDF and http://www.smoke-free.ca/factsheets/pdf/Emissions3a.PDF
A calculator for your current exposure to the chemicals found in tobacco smoke, for smokers and non-smokers: What am I inhaling? http://www.smoke-free.ca/Health/ETS_inhaling.htm
[1] online report: Action on Smoking and Health, Fact Sheets: The Constituents of Tobacco Smoke July 2000. -see: http://www.ash.org.uk/html/factsheets/html/fact12.html
[3]article, available online: American Council on Science and Health, "Priorities for Health" journal, Vol 2 Number 4, 1990: http://www.acsh.org/publications/priorities/0102/nicotine.html "What's in a Cigarette?" by K. H. Ginzel, M.D.
[4] report, available as .pdf online: U.S. Surgeon General Report . Reducing the health consequences of smoking. 1989. Available at : http://www.cdc.gov/tobacco/sgr_1989.htm . pp 86-7.
[5] US Surgeon General. The Health Consequences of Smoking: Chronic obstructive lung disease. USGPO, 1984.
[6] book: David Bodanis, The Secret House, Simon & Schuster, New York, 1986, p. 184-5.
[7] book, available online: Royal College of Physicians. Nicotine Addiction in Britain. 2000. Section 2.2. Available online at : http://www.rcplondon.ac.uk/pubs/books/nicotine/index.htm